With the advent of two predominant frequency bands for reception of satellite repeater television communication, the Ku band and the C band significant advances have been needed in feed horn assembly designs. It has been the desire to develop truly coaxial feed assemblies and this I have achieved in my co-pending application, Ser. No. 105,135, now U.S. Pat. No. 4,903,037. In that dual frequency feed, a pair of cavities or open-ended circular waveguides are located coaxially with the Ku band cavity located inside of the C band cavity. A rotatable probe is located in each cavity and they are coupled together for simultaneous rotation from a common drive source with the drive shaft preferably entering from the rear of the C band cavity.
The coupling of the Ku band probe has presented some difficulty since its normal exit direction through the rear of the C band cavity would place it in direct interference with the C band probe. I avoided this problem with my co-pending application by the use of a radically extending coaxial line. Other approaches to coaxial dual frequency feed assemblies are illustrated in the following U.S. Patent:
______________________________________ U.S. Pat. No. Inventor Issued ______________________________________ 4,740,795 John M. Seavey April 26, 1988 ______________________________________
The foregoing constitute, a rather complex structure, both mechanically and electrically. Single frequency band feeds with the signal from the probes being extracted from the rear of the feed are illustrated in the following:
______________________________________ U.S. Pat. No. Inventor Issued ______________________________________ 4,528,528 E. P. Augustin July 9, 1985 4,414,516 H. T. Howard November 8, 1983 4,554,553 F. Grim November 19, 1985 4,504,836 J. M. Seavey March 12, 1985 ______________________________________
A single frequency band system does not encounter the problem of mechanical and electrical interference between the probes and their coaxial lines.